Vat dye composition



Patented Aug. 13, 1940 UNITED v STATES PATENT OFFICE 2,211,126 VAT DYEcoMPosrnoN Jean G. Kern, Buffalo, Y2, assignor to National Aniline &Chemical Company, Inc. New York, N. Y., a corporation of New York NoDrawing.

solutions or dispersions for coloring textile;nia-- terials and thelike. The vat dye past'es' or p w;

ders are particularly valuable for preparation of printing pastes andpaifdin'gbaths. The invention also includes processes for making the vatdye compositions.

In the art of dyeing with vat dyes, two general methods are ordinarilyemployed. In accordance with one method, a vat comprising analkalinesolution of a reduced vat dye isprepared and the fibrousmaterial to be dyed is worked in this solution whereby the fiber takesup the reduced compound of the dye. The material is then subjected tooxidation and other finishing treatments to convert the vat dye from thereduced to the unreduced form and further complete the fixing of the dyeand finishing of the material. In accordance with the other method thedye is applied to the material to be dyed while in the unreduced form;it is then subjected to a reducing treatment whereby the dye 'isconverted to the soluble form in the presence of the fiber and is thentaken up by the fiber. It is then subjected to oxidation and/or otherfinishing treatments to fix the dye on the fiber, remove undesiredresidual material, and complete the finishing of the material.

In dyeing with vat dyes by the latter method, one of two procedures isusually followed, depending upon'whether the material is to be dyed asolid color or with a pattern in one or more colors. If the material isto be dyed a solid color, the pigment padding (pad and jig) ,process isordinarily employed, andif the material is to be dyed with a pattern,the printing process is generally utilized. 1

In the pigment padding process, the unreduced vat dye in finely-dividedform is suspended in a suitable suspension medium, usually watercontaining added materials such as thickeners and alkaline substances.The material to be dyed is passed through thissuspension, the fibermechanically picks up the particles of insoluble dye, and the materialis subsequently worked in a reducing bath whereby the dye is'reducedtothe the dye to the insoluble form, fix it on the fiber,

and further complete the finishing of themate- 55 rial..

- paste.

soluble-form and is absorbed and/or adsorbed by the fiber. The materialis finally subjected to.

Application January 28, 1939, Serial No. 253,347

The printing process of dyeing a textile fabric generally involvesapplying a so-called printing paste to the fabric in the form of adesign (e. g., by means of a screen, a stencil, or an engraved 'roll),and then subjecting the printed fabric to 5 further treatment to fix thedye. In general, vat

dye printing pastes, in addition to the unreduced vat dye, containsubstances which in themselves do notreduce the vat dye under theconditions of Y the printing operation but which in subsequent 10operations react with the dye to convert it to the soluble form (suchassodium formaldehydesulfoxylate and potassium carbonate), othersubstances or assistants which promote the reduction of the dye and/orabsorption of the reduced 15 compound by the fiber, and suitable gums orthickeners. The fixing treatment usually comprises subjecting theprinted fabric to a so-called' steaming or ageing treatment to inducereduction of the vat dye by the action of the re- 20 ducing agentpresent on the fabric, and cause the reduced dye to be taken up by thefiber. The fabric is then subjected to oxidizing, washing, and otherfinishing treatments.

In dyeing with the vat dyes, particularly by the pigment padding orprinting processes, the success of the operation is in a large measuredependent upon the uniformity with which the vat dye (e. g., theunreduced vat dye) is applied to the fabric. The vat dyes in unreducedform, as is well known, are insoluble in water and are not readilywettedby water. In preparing a padding bath or printing paste it isimportantthat the vat dye be in finely-divided form, that it be uniformlydistributed throughout the bath or paste, and in condition such that itmay be taken up'by the fiber. Further, it is important that the vat dyebe capable of rapid and substantially complete reduction to the reducedform. The vat dyes, especially those which are intended for use in thepigment padding and printing processes, are generally marketed in theform of so-called dye pastes or color pastes, and dye powders. A dyepaste of this kind is usually an aqueous mixture or suspension offinely-divided -vat dye, whichge'nerally makes up 10 to 20 per cent orthe Th'paste usually contains a small amount of a dispersing agent suchas Leukanol (a'condensation' product of formaldehyde and a Tnaphthalenesulfonic acid) and the remainder is main! from ordinary vatdye pastes.

poly-glycols, etc. These vat dye pastes are ordinarily produced bystirring the dispersing and other agents with the filter cake of the dyeresulting from filtration of a precipitate of the dye obtained in itsmanufacture, or by precipitation in the finely-divided form from a vatof sulfuric acid or other solution.

As noted above, vat dyes for use in the preparation of padding baths andprinting pastes may be supplied in the form of vat dye powders. In thecase of the powders, it is important that the vat dyes contained thereinnot only have the properties pointed out above in connection with thevat dye pastes, but also that the powders be rapidly converted touniform suspensions of the vat dye. Especially successful vat dyepowders are described in my United States Patents Nos. 2,067,926 and2,145,193. These vat dye powders are prepared by incorporating with theusual vat dyepaste (e. g., one containing a small amount of a dispersingagent) a soluble salt of an acid alkyl ester of an oxygen-containingpolybasic inorganic acid (e. g., a soluble salt of a sulfuric acid esterof a lower aliphatic alcohol) and preferably also an added substancesuch as, for example, dextrine, sugar, gum arabic, and the like, andthen drying and grinding the resulting composition.

It is the principal object of the present invention to provide vat dyecompositions which are productive of excellent dyeings and printingswhen employed in the usual ways. Anotherobject of the invention is toprovide vat dye pastes and powders which are adapted for use in theeflicient preparation of padding baths and printing pastes containinguniformly distributed therethrough the finely-divided particles of thevat dyes. Another object of the invention is to provide vat dye pastesand powders .which when used in the preparation of padding baths andprinting pastes are productive of compositions characterized by themarked eiiiciency with which the dye is initially taken up by the fiberandthe increased brilliancy and strength of the resulting dyeings andprintings as compared with the dyeings and printings obtained by the useof padding baths and printing pastes prepared A further object of theinvention is to provide vat dye pastes which remain fluid on standingand which may be easily and quickly mixed with the ingredients making upthe conventional padding baths and printing pastes to form homogeneouscom-. positions containing the vat dyes in well-dispersed condition.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

It has been found in accordance with the present invention that theproperties of vat dye compositions containing a vatdye in the unreducedor other form can be improved by incorporating in them a soluble organicester of an organic polycarboxylic acid (e. g., an allphatic or aromaticpolycarboxylic acid) and an organic hydroxy compound free from aliphaticradicals containing a total of more than 12 allphatic carbon atoms peraliphatic radical and from aliphatic radicals containing more than 8aliphatic carbon atoms in a straight carbon chain, which ester containsin the acyl radical thereof an unesterified carboxyl group as the solesolubilizing group. In speaking of soluble esters herein it is meantesters that are soluble in water and/or in alkaline solutions. It hasbeen found that esters of this class, particularly the esters ofaliphatic carboxylic acids, possess a combination of properties whichmake them valuable for use in compositions containing vat dyes, andespecially in vat dye compositions in paste or powder form intended foruse in the preparation of padding baths or printing pastes.

In preparing a vat dye paste in accordance with the present invention, avat dye, usually in the form of a press cake (a mixture of a vat dye infinely-divided form with water as obtained in the course of manufactureof the dye) is mixed with an ester of the above class and alsopreferably with a dispersing agent (for example, Leukanol or sulfltewaste liquor). The resulting mixture is then diluted with water to thedesired dye-strength; or if the paste is to be a so-callednon-dryingpaste, that is to say, one in which the water is replaced in whole orpart by a water miscible high-boiling alcohol such as iso-butyl alcohol,glycerine, glycol, poly-glycerines, poly-glycols, and alkyl ethers ofthese compounds, the requisite amount of such alcohol is added to themixture and water is removed therefrom by evaporation until the pastehas the desired dye strength. The compositions prepared in this waycomprise fluid pastes consisting of dispersions of the finely-dividedvat dye. The compositions are relatively stable and do not settle onstanding over a relatively long period of time. Furthermore, as comparedwith many available vat dye pastes, they are in a fluid or free-runningstate. Thus they are adapted to be efllciently 'and quickly incorporatedwith the other ingredients of padding baths and printing pastes toprepare such baths and pastes in a form such that the resultingcompositions may be efficiently employed in dyeing and printing.

When preparing the vat dye compositions of the present invention in theform of vat dye powders, the paste prepared as described above, butusually with little or no high-boiling watermiscible alcohol therein,may be concentrated and/or dried as by means of a vacuum or atmosphericrotary drum drier by spray drying or by means of the addition to thepaste of an anhydrous hydrate-forming inorganic salt. It is preferable,however, when preparing the. powders to add to the paste before drying asubstance such as sugar, dextrine, gum or starch, or derivations ofalginic acids and/or other suitable additions. In preparing the dryproducts employing a mechanical drier, the dry product scraped from thedrier is in the form of flakes,

scales, or grains, and may be used as such, but i may also be ground toproduce a finely-divided powder.

The esters employed in the vat dye compositions of the present inventionare such as are derivable from aromatic polycarboxylic acids,

The said esters may be derivatives of aliphatic mono-hydric orpoly-hydric alcohols, or of mono-, or poly-hydric hydro-aromaticalcohols, cycloaliphatic alcohols, heterocyclic alcohols, aralkylalcohols, mixed aliphatic-hydro-aromatic alcohols, or of monoandpoly-hydric alcohol'ethers. As examples of such alcohols there may bementioned ethyl, propyl, allyl', butyl, amyl, hexyl, heptyl, octyl, andthe like alcohols; cyclohexanol, methyl cyclohexanol, cyclopentanol,tetrahydrofurfuryl, alcohol, benzyl' alcohol, phenyl ethyl alcohol,phenyl methyl carbinol, the various terpene alcohols, ethylene,propylene, di-ethylene and tri-ethylene glycols, and the like; and themethyl and ethyl ethers of ethylene, diethylene or other glycols. Astypical alcohols there may be also mentioned the following alcoholswhich are obtainable as vby-products in the production of methanol bythe catalytic hydrogenation of mixturesof carbon monoxide and carbondioxide: 4-methyl-1-pentanol; 2-methyll-pentanol;2,4-dimethyl-l-pentanol; 3-methyl- Z-pentanol; 2,4 dimethyl 3 pentanol(di-isopropyl-carbinol) 2-methyl 3 pentanol; 4- methyl-l-hexanol2,4-dimethyl-1-hexanol; 2,5- dimethyl-3-hexanol; Z-ethyl-butanol; andothers of like character.

The above parent alcohols may be primary or secondary but all of themare characterized by containing no aliphatic radicals containing morethan 8 aliphatic-carbon atoms in a straight carbon chain. The estersderived from alcohols wherein the direct chain between the esterifiedalcohol function and the nearest branching point in the ester group(alcohol residue) is not long-' er than 4 or at most 6 carbon atoms, areparticularly valuable for use in the vat dye compositions.

Where in the appended claims an ester of an alcohol and an aromatic oraliphatic carboxylic acid is referred to it will be understood that anester derivable from an alcohol selected from any of the above describedclasses and an aromatic or aliphatic carboxylic acid is intended, unlessotherwise indicated.

It will be understood that the alcohols from which the esters arederivable may contain substituents which do not alter the essentialphysical or chemical characteristics of the esters. As indicated above,polyhydric alcohols may be employed and in this case either one or bothof the hydroxyl groups may be esterified with the carboxylic' acid groupof the acid employed. When only one of the hydroxyl groups isesterified, one or more free hydroxyl groups remain, which are notobjectionable and in some cases appear to have an advantageouseffect-upon the properties of the esters. The amino group may also bementioned as an example of a substituent which may be present in thealcohol residue of the esters, valuable esters adapted for use in thevat dye compositions being derivable from amino alcohols. Also, thealcohols may contain alkylamino substituents.

Although any of the above described esters may be used with advantage intheyat dyecompositions of the present invention, .it will be understoodthat these esters will vary in'degree in their possession of thevaluable properties characteristic of the class. It has been found thatthe best results are obtained with esters of the above class whichdisplay high solubility in aqueous so,- lutions and/or alkaline printingpastes; Accordingly, the preferred esters are those which are derivedfrom loweraliphatic alcohols (is, containing 2 to 6 carbon atoms),cycloalkyl alcohols, and aromatic alcohols. It has been found thatesters which are derivatives of isobutyl alcohol are of markedly highvalue. For similar reasons the esters that are derivatives of aliphaticpolycarboxylic acids, particularly those that contain from 3 to 6 carbonatoms, are preferred for use in the compositions of the invention.

In view of the foregoing disclosure, it will be readily apparent that alarge number of esters are available for use in the compositions of theinvention. The following esters (described in the form of the freeacids) are given as examples of typical esters of theclass hereinabovedisclosed: isobutyl acid .phthalate, isobutyl acid succinate,p-carboxyl-isobutyl cinnamate, mono-n-amyl adipate, mono-isobutylpyrotartrate, and monoisopropyl glutarate. It has been .found that ofthe above esters, isobutyl acid succinate, particularly in the form ofthe sodium salt, produces especially valuable results when incorporatedin vat dye compositions.

The esters are preferably employed in the form of their neutral solublesalts. The alkali metal salts, or the salts obtained by neutralizing theacid esters with organic derivatives of ammonia, are especiallyimportant. As examples of suitable organic derivatives of ammonia, thefollowing are mentioned: the alkylolamines (e. g.,

"mono-db, or triethanolamine); the alkylol diamines, (e. g.,1,2-di-(2'-ethanolamino) ethane and 1,3-di-(2'-ethanolamino)-2-propanol) the quaternary alkylolamines, the diquaternaryalkylolamines (e. g., tetra-hydroxy-ethylamine ammonium hydroxide. hexahydroxy ethyl ethylene diammonium hydroxide); and the quaternaryaralkyl-alkyl ammonium hydroxides or the aralkyl-hydroxyalkyl-ammoniumhydroxides (e. g., tri-methyl-benzyl ammonium hydroxide, tri-(hydroxy-ethyl) -benzylammonium hydroxide, etc.).

The valuable effects resulting from the inclusion of the above describedesters in vat'dye-coinpositions in accordance with the present inventionare noticed both in vat dye pastes and powders from which dyeingcompositions (baths and printing pastes) are prepared and also in thedyeings and printings obtained with the ultimate compositions.

The value of vat dye compositions is primarily dependent upon theexcellence of the dyeings and printings obtained therefrom. The physicalform of vat dye pastes and powders prior to their use bined orcommingled with the vat dye particles,

as to form therewith a composition resembling a solid dispersedsuspension. The particles of the vat dyes, therefore, are prevented fromcombining to form larger particles which. would be difilcult todisperse'in a padding bath or printing paste.

When the vat dye pastes and powders are incorporated with the otherusual ingredients of vats, padding baths, or printing pastes, severaladvantageous results are obtained. First, as predyeing or printingtextiles.

viously noted, the compositions may be mixed readily with suchingredients to form homogeneous dyeing compositions. Further, it appearsthat the esters act to increase the solubility of leuco vat dyes andincrease the strength and brilliancy of the dyeings and printingsobtained. This is because, while leuco vat dyes are regarded as beingsoluble in alkaline solutions, and because of this solubility may betaken up by the fiber to be dyed, they are not freely soluble and theirincreased solubility caused by the esters accelerates the rate of theirabsorption or adsorption by the fiber.

The vat dye compositions of the present invention are particularlyvaluable as compared with ordinary vat dye compositions when they areapplied to synthetic fibers composed of regenerated cellulose, or tounbleached natural fibers, such as cotton and raw silk. It is known thatthese latter fibers do not, as a rule, readily absorb the reduced vatdyes because of their coating of natural waxes which act as resistagents.

As before stated, the soluble esters of this invention may be used perse or in admixture with other substances ordinarily used in the art ofThese substances may, be in the nature of the alkyl partial inorganicesters specifically disclosed in my patents above referred to, othersubstances used in dyeing and printing, such as the alkylolamines,polyhydric alcohols, and ethers, e. g., the ethers of diethylene glycol,glucosic compounds, dextrines, gums, starches, etc., or compounds in thenature of printing catalysts, such as heavy metal compoundsor the heavymetal salts of alkyl partial esters, such as isobutyl-nickel-sulfate, orthe heavy metal salts of the soluble carboxylic esters of the presentinvention, themselves.

Inasmuch as the quality and dispersibility of the resulting dyecomposition are dependent to a considerable extent upon the originaldegree of dispersion of. the dye in the suspension or in the dry form,the vat dye is preferably treated in the highly dispersed form. Asuitable dispersing agent is preferably incorporated into the disprsionor suspension so as to aid in preventing precipitation and agglutinationof the dye particles during storage or during the drying and to increasethe fluidity and render easier the incorporation of the soluble salts ofthe carboxylic acid esters.

Among the dispersing agents which may be employed for this purpose theremay be mentioned, for example, the sulfonic acids of benzene,hydroxybenzenes, naphthalene, hydroxynaphthalenes, their nuclear alkyl,nuclear aralkyl, and hydrogenated derivatives, as well as aldehydecondensation products thereof (as for example, 2,6-napthalene-disulionicacid, 1,7-naphthalene- -disulfonic acid, 2,8-naphthalene-disulfonicacid,

isopropyl-naphthalene-sulfonic acids. dibutylnaphthalene-sulfonic acids,amylnaphthalenesulfonic acids, butyl-benzyl-naphthalene-sulfonic acids,cyclo-hexylnaphthalene-sulfonic acids,methylene-d1(p-naphthalene-suli'onic acid, methylene-di(di-isopropyl-naphthalene-sulfonic acid) in the form of the free acidsor salts (e. g.,.alkali metal salts), etc.; sulfite cellulose wasteliquors and their mildly oxidized products and evaporated residues;sulfonated resins; abietene, abietine and abietane sulfonic acids;soaps; sulfonated higher fatty acids, fats and oils; and the like, aswell as mixtures of two or more of such substances.

Further, additional substances having diluent,

anti-foaming, assisting, wetting, catalytic, enolyzing, or othersuitable action in the subsequent use of the compositions may also beincorporated into the compositions of the present invention, preferablywhile the latter are in the form of aqueous suspensions or in the formof non-drying pastes containing high boiling alcohols or alcohol ethers.

In preparing the vat dye pastes and powders in accordance with apreferred manner of proceeding, the mixture of vat dye in aqueous orhigh boiling solvent dispersion is agitated with the appropriate amountof the carboxylic acid ester salt together with the other substances, ifadded, until a homogeneous paste is formed, or the mixture of theaqueous suspension of the dispersed vat dye and a carboxylic acid estersalt together with the other substances, if added, is evaporated withagitation until a thick paste is formed, with or without the aid ofvacuum and preferably at a temperature not exceeding 100 C. Theresulting paste constitutes a valuable vat dye paste. If desired, it maybe brought to substantial dryness to form a dry vat dye composition.Thus, the paste may be evaporated to dryness on an atmospheric or vacuumrotary drum drier, and the dry product scraped off in the form offlakes, scales, or grains which may be used as such, or the paste, withor without preliminary evaporation, may be admixed with a suitablehydrateforming'soluble salt in an anhydrous condition, such as anhydroustrisodium phosphate, and the admixture stirred to produce a dry product.If desired, the dry product may be disintegrated in any suitable mannerinto a powder.

Mixtures of the carboxylic acid ester salts or mixtures of them with'alkyl inorganic ester salts, disclosed in .my patents referred to abovemay also be employed in accordance with the present invention. Further,the esters used in the com positions of the invention may be usedtogether with or in place of the esters disclosed in my applicationsSerial Nos. 253,345 and 253,346, filed of even date herewith.

The amount of the soluble carboxylic acid esters employed in thepreparation of the compositions of the present invention may be variedover a considerable range, depending in part upon the concentration ofvat dye in the composition, the use to which the composition is to beput, and whether or not other diluents and other materials having acatalytic, assisting, wetting, enolyzing, dispersing. or other action,are included in the composition.

The invention may be employed in connection with vat dyes of all typesincluding those derived from anthraquinone, indophenols, variousindigoid, thioindigoid and indirubin compounds, etc.; as for example,indanthrones, pyranthrones, fiavanthrones, dibenzanthrones,isodibenzanthrones, perylene vquinones, anthranthrones, dibenzpyrenequinones, anthrimido-carbazoles, naphthacridones, indigo, thioindigo,indirubin, etc., including derivatives thereof, such as their halogen,nitro, sulfur and/or alkoxy derivatives.

It should be noted that while the vat dyes in the compositions of theinvention are preferably in the unreduced form, they may also be in thereduced or leuco form. For example, leuco ester salts of vat dyes andleuco compounds of vat dyes prepared by careful acidification of analkaline v'at, or by other methods, may be used, if desired.

, Although it is generally preferable and desirable, in order to takefull advantage of their properties, to employ the esters in vat dyepastes or powders which are used in the preparation of padding baths orprinting pastes, the esters may also be mixed with the other ingredientsused in padding baths or printing pastes at the time these compositionsare prepared. In proceeding in this way, the dye may be introduced intothe mixture in the form of a press cake or an ordinary dye or other formof paste, the ester or esters being added at any desired or suitablepoint in the preparation of the compositions.

In the foregoing description, the use of the vat dye compositions in thedyeing and/or printing of textile materials has been stressed since thisis the most important application of the compositions. The compositions,however, especially when in the form of powders, may be used in thepreparation of dispersions of vat-dyes for use in the pigment form inthe dyeing of paper, the tinting of fibers and other materials, and thelike. The ready dispersibility of the compositions makes them especiallyvaluable for such purposes.

The invention will be further described in connection with the followingspecific examples (in which the parts are by weight), which are given toillustrate the invention. It will be realized, however, that theinvention is not limited thereto but that changes may be made in thematerials treated and their proportions, manipulative steps, and otherconditions without departing from the scope of the appended patentclaims.

Example 1.400 parts of indigo paste (con-- taining 20% of pure indigo asshown by indigotine titration and resulting from the precipitation ofindigo from an alkaline solution of indoxyl by aeration) are stirredwith two parts of Leukanol until a thin fluid paste is obtained.

13 parts of cane sugar and parts of normalbutyl sodium succinate arethen added, the mixture is stirred until solution of the mono-butylsuccinate is complete, and the resulting mixture is evaporated withstirring until a thick paste is formed. The thick paste is then placedin drying pans and evaporated to dryness. The dry product is ground andscreened.

There is thus obtained an indigo powder containing 80 per cent of indigowhich, when added Instead of the normal-butyl sodium succinate,

an equal amount of isopropyl sodium succinate. or amyl sodiumpyrotartrate may be used.

Example 2.To 100 parts of the chlorinated indanthrone vat dye known asNational Carbanthrene Blue BCS (Color Index #1114) in the form of anaqueous suspension or commercial paste containing 18 per cent of totaldye solids, there are added, with stirring, 2 parts of Leukanol (or 6parts of a 30 per cent solution of Leukanol), 50 parts of cane sugar,and 25 parts/of dextrine. The suspension is stirred until homogeneous,and then 5 parts of sodium isobutyl phthalate are added and the mixtureis stirred until solution of the monoalkyl phthalate is complete. Theresulting mass, either as such. or after evaporation, may be used as apaste; or it may be evaporated to dryness, ground and screened, as inExample 1, to produce a powder that is readily dispersed when added towater. The product, either in the form of paste or powder, gives uniformdyeings of high tinctorial value when employed to dye fabrics inaccordance with standard practice, and especially by the pad and jigmethod. Instead of the sodium isobutyl phthalate, any one of the solublecarboxylic acid esters herein disclosed may be used.

Example 3.-100 parts of the thioindigoid vat dye known as National VatOrange R (Color Index #1217) in the form of an aqueous paste containingabout 11 per cent of dye solids, are mixed with 2 parts of Leukanol and87 parts of sodium p-carboxy-isopropyl cinnamate until solution of thelatter is complete. The resulting suspension is evaporated to dryness,ground and screened. Instead of the sodium p-carboxy-isopropylcinnamate, equivalent amounts of the. neutral sodium salt of themono-n-amyl ester of adipic acid may be employed. 100 parts of a VatOrange R powder are thus.obtained which, when employed in thepreparation of. a printing paste (for example, by mixing 150 parts ofthe powder with 200 parts of British gum, 140 parts of potassiumcarbonate, 80 parts of sodium formaldehyde sulfoxylate, 50 parts ofglycerine, and 380 parts of water) and. utilized in the printing ofrayon materials in accordance with the usual proneutral solublecarboxylic acid ester salt results in a much greater brilliancy of shadeand more complete penetration of the material, so that in many'instances there are no back sides and the fastness to crocking is muchenhanced.

Example 4.-To 100 parts of National Carbanthrene Blue GCD Double Paste(Color Index #1113) containing 16.5 per cent of dye solids and 1 percent of Leukanol, there are added-50 parts of sodium isopropyl glutarateand 32.5 parts of urea, and the mixture is stirred until the latter aredissolved. The resulting suspension is evaporated to dryness, ground andscreened. A very readily dispersible vat powder is obtained which issuitable for printing as well as dyeing.

In place of sodium isopropyl glutarate, any one or a mixture of theneutral sodium salts of monoalkyl carboxylic esters hereinbeforementioned can be used.

As before stated, the esters described above can be employed in'compositions containing any vat dye. which may be present in thecompositions of the invention:

The following are examples of vat dyes I claim:

1. A vat dye composition comprising a vat dye compound and a solubleorganic ester of an organic poiycarboxylic acid, said ester containingat least one unesterified carboxyl group inthe acyl radical and beingfree from other solubilizing groups, said ester being free fromaliphatic radicals containing a totalof more than 12 aliphatic carbonatoms and from aliphatic radicals con- I taining more than 8 aliphaticcarbon atoms in a as the-sole solubilizing group, said ester being freefrom aliphatic radicals containing a total of more than 12 aliphaticcarbon atoms and from aliphatic radicals containing more than 8aliphatic carbon atoms in a straight carbon chain.

3. A vat dye composition comprising a vat dye compound and a solublesalt of an organic ester of an aliphatic polycarboxylic acid containingnot more than 8 carbon atoms, said ester containing an unesterifiedcarboxyl group in the acyl radical as the sole solubilizing group, saidester being free from aliphatic radicals containing a total of more than12 aliphatic carbon atoms and from aliphatic radicals containing morethan 8 aliphatic carbon atoms in a straight carbon chain.

4. A vat dye composition comprising a vat dye compound and a solublealkali metal salt of an ester of an aliphatic alcohol and an aliphaticpolycarboxylic acid containing not more than 8 carbon atoms, said estercontaining an unesterifled carboxyl group in the acyl radical as thesole solubilizing group, said ester being free from aliphatic radicalscontaining a total of more than 12 aliphatic carbon atoms and fromaliphatic radicals containing more than 8 aliphatic carbon atoms in astraight carbon chain.

5. A vat dye composition comprising a vat dye compound and a-solublealkali metal salt of a mono-ester of an unsubstituted aliphaticdicarboxylic acid containing 3 to 6 carbon atoms with an aliphaticalcohol containing 2 to 6 carbon atoms.

6. A vat dye composition comprising a vat dye compound and a solublealkali metal salt of a mono-ester of an aromatic dicarboxylic acid ofthe benzene series and an aliphatic alcohol containing 2 to 6 carbonatoms.

7. A vat dye composition comprising a vat dye compound and a solublealkali metal salt of a butyl ester of an organic polycarboxylic acid,said ester containing an unesterified carboxyl group in the acyl radicalas the sole solubilizing ro 8. A vat dye composition comprising a vatdye compound and a soluble alkali metal salt of an organic mono-ester ofsuccinic acid, said ester being free from aliphatic radicals containinga total. of more than 12 aliphatic carbon atoms and from aliphaticradicals containing more than 8 aliphatic carbon atoms in a straightcarbon chain.

9. A vat dye composition comprising a vet dye compound and a solublealkali metal salt of a mono-ester of succinic acid and analiphatic'alcohol containing 2 to 6 carbon atoms.

10. A vat'dye composition comprising a vat dye compound and sodiumisobutyl phthalate.

11. A vat dye composition comprising a vat dye compound and sodiumisobutyl succinate.

12. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a dispersingagent, and a soluble organic ester of an organic polycarboxylic acid,said ester containing at least one unesterifled carboxyl group in theacyl radical and being free from other solubilizing groups, said esterbeing free from aliphatic radicals containing a total of more than 12aliphatic carbon atoms and from aliphatic radicals containing more than8 aliphatic carbon atoms in a straight carbon chain.

13. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a dispersingagent, and a soluble salt of an organic ester of an allphaticpolycarboxylic acid containing not more than 8 carbon atoms, said estercontaining an unesterifled carboxyl group in the acyl radical as thesole solubilizing group, said ester being free from aliphatic radicalscontaining a total of more than 12 aliphatic carbon atoms and fromaliphatic radicals containing more than 8 allphatic carbon atoms in astraight carbon chain.

14. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a dispersingagent,-

and a soluble alkali metal salt of an aliphatic alcohol and an aliphaticpolycarboxylic acid containing not more than 8 carbon atoms, said ester.

containing an unesterified carboxyl group in the acyl radical as thesole solubilizing group, said ester being free from aliphatic radicalscontaining a total of more than 12 aliphatic carbon atoms and fromaliphatic radicals containing more than 8 aliphatic carbon atoms in astraight carbon chain.

15. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a,dispersingagent, and a soluble alkali metal salt of a mono-ester of anunsubstituted aliphatic dicarboxylic acid containing 3 to 6 carbon atomswith an aliphatic alcohol containing 2 to 6 carbon atoms.

16. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a dispersingagent, and a soluble alkali metal salt of a butyl ester of an organicpolycarboxylic acid, said ester containing an unesterified carboxylgroup in the acyl.

radical as the sole solubilizing group.

17. A vat dye paste adaptedfor use in the preparation of printing pastesand padding baths comprising an unreduced vat dye, a dispersing agent,and a soluble alkali metal salt of a mono-ester of succinic acid and analiphatic alcohol containing 2 to 6 carbon atoms.

18. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye,.a dispersingagent, and sodium isobutyl phthalate.

19. A vat dye paste adapted for use in the preparation of printingpastes and padding baths comprising an unreduced vat dye, a dispersingagent, and sodium isobutyl succinate.

JEAN G. KERN.

